The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.
@article{arxiv.1004.1556,
title = {Migration of nuclear shell gaps studied in the d(24Ne,p gamma)25Ne reaction},
author = {W. N. Catford and C. N. Timis and R. C. Lemmon and M. Labiche and N. A. Orr and B. Fernandez-Dominguez and R. Chapman and M. Freer and M. Chartier and H. Savajols and M. Rejmund and N. L. Achouri and N. Amzal and N. I. Ashwood and T. D. Baldwin and M. Burns and L. Caballero and J. M. Casadjian and N. Curtis and G. de France and W. Gelletly and X. Liang and S. D. Pain and V. P. E. Pucknell and B. Rubio and O. Sorlin and K. Spohr and Ch. Theisen and D. D. Warner},
journal= {arXiv preprint arXiv:1004.1556},
year = {2010}
}